Electric switch



F. DRING ELECTRIC SWITCH July 14, 1931.

Filed Jan. 3.` 1929 Patented July 14, 1931 UNITED 'STATESu PATENT y OFFICE FRITZ DRING, OF BERLIN-FROHNAU, GERMANY, ASSIGNOR TO SIEMENS-SCHUCKERT- WERKE AKTIEQ'GESELLSCHAFT, OF BERLIN, SIEMENSSTADT, GERMANY, A GERMAN CORPORATION Application led January 3, 1929, Serial No. 330,024, and in Germany January 9, 1928.

My invention relates to improvements in electric switches operated by compressed gas, and more particularly to electric switches operated by compressed air and particularly suitable for controlling hightension circuits.

My invention consists of a switch of this type in which the contact member is closed or opened by means of a single piston and in such a manner, that when the compressed Vair is turned on the piston brings the contact member into the closing position and that when the compressed air is cut off the piston returns into its inoperative position and thus causes the return of the contact member into the ofi position.

A further object of my invention is to make the contact pressure of the switching member independent of the fluctuations of the air pressure.

Another object of my invention is to cause the contact member to snap back quickly into the o' position, the rate of motion being independent of the return speed of the piston and the dropping of the air pressure.

My invention consists substantially in operating by means of the piston, actuated by compressed air, a contact member, which is movable independent of the piston and stands under the control of a special spring arrangement having the tendency to press the contact member against the piston. lThe general arrangement is such, that at the end of the piston stroke the contact member is arrested in the closed position by an eX- changeable holding device and that the piston, receding into its inoperative position without entraining the contact member when the air pressure drops, releases at the end of its return stroke the holding device,

whereupon the contact member snaps back into the o position.

An embodiment of my invention is illustrated in the drawings affixed hereto and forming part vof my specification.

In these drawings Fig. 1 illustrates my improved switch in sectional elevation and in o position,

Fig. 2 the same switch in closed position with the contact member arrested by the holding device, and

Fig. 3 the movable Contact member and the stationary contact members detached from the switch.

Like parts are indicated by like numerals of reference in the various figures of the drawings.

Referring to the drawings, 1 is a stationary cylinder fixed to the upper portion of the main switch frame 1a, the cylinder containing the piston 2. The compressed air is supplied through the pipe Sprotruding through the top of the switch frame. In the movable shell or housing 5 surrounding the piston and cylinder is disposed a helically coiled spring 4, which at its upper end abuts against the housing 5 and with its lower end against a flange on the cylinder 1. Belowl the housing 5 is located a transverse bar 6, which is connected with the tension plate 8 by two rods 7. A helical compression spring 9 connectspthe tensionY plate 8 with a guide rod 10, which is iXed on the brush holder 11 carrying the laminated contact brushes 12. The brush holder 11 is supported on the frame of the switch by a second compression spring 16, which always tends to throw the brush holder 11 upwardly. On the framework of the switch are mounted two arms 18 which by springs 19 are forced toward the transverse bar 6 and are each provided with a latch 14. Nor-l 18 are spread apart by lugs 15 provided on housing 5, so that latches 14 are held away from the ends of bar 6.

If the compressed air valve (not shown) for controlling the switch is opened, the compressed air entering through the pipe 3 forces the piston 2 downward. The piston bearing against spring housing 5 overcomes the resistance of the comparatively strong spring 4, which tends to force the piston 2 upward. During its descent the piston 2 carries along the spring housing 5 and through the transverse bar 6 and the tension plate 8 connected with it by the rods 7 the spring 9 and the rod 10 together with the holder 11 of the contact brushes 12. Near spreads brushes 12 apart on the stationary' contact plates 13, the contact brushes being kept under tension by means of the spring 9.

Shortly before the piston 2 reaches its lowest position lugs 15 on housing 5 release arms 18 so that the latches 14 snap .behind the transverse bar 6 and hold itn 1n the switch closing position shown in Fig. 2. The switch now remains locked in the closed position independent of fluctuations of the pneumatic pressure.

If the pressure in the air supply pipe 3 drops a substantial amount the piston 2 creeps back toward its uppermost osition under the action of the spring 4. or the larger art of this return motion of the iston t e transverse bar 6 is still detained y the latches 4, so that the electric contact remains closed for the time being.

Shortly before the piston reaches its uppermost position, arms 18 are spread apart by lugs 15 on the sprin housing 5, so that I the latches 14 release t e transverse bar 6 and the contact brushes are pushed upward by spring 16 into the off position. To prevent burnin of the brushes auxiliary arc tips17 pre erably of carbon, are easily exchangeably mounted upon the laminated copper brushes 12.

It will be understood that the construction of the individual parts of the switch may be varied within wide limits. The compression springs may, for instance, be replaced by tension springs. The movable latches may be mounted on the transverse bar and engage projections on the switch frame, and many other equivalent modifications will suggest themselves to those skilled in the art. l

I claim as my invention:

1. In an electric switch operated by compressed gas, in combination, a cylinder having an extension for connecting an air pipe, a piston disposed to reciprocate in said cyllnder, and a spring arrangement tending to keep said iston in its position of rest, a contact device operated by said piston, a locking device for maintaining said contact .device in contact closing position durin the major portion of the return stroke 0 the piston, means operated by said piston for releasing said locking device near the end of the return stroke of said piston, and a spring tending to return said contact device into its inoperative open contact position.

2. In an electric switch operated by compressed gas, in combination, a cylinder having an extension for connectmg an air plpe,

a piston disposed to reciprocate in said cyhnder, and a spring arrangement tending to keep said piston in its position of rest, comprising a helical spring, a housing surrounding said piston for the reception of said spring, sald spring abuttingI with one end against said housing and with the other end against said cylinder, a contact device operated by said piston, a locking device for maintaining said contact device in Contact closing position during the major portion of the return stroke of the iston, means erated by said piston for re easing said locking device near the end ofthe return stroke of said piston, and a spring tending to return said contact device into its inoperative open contact position.

3. In an electric switch operated byl compressed gas, in combination, a cylinder having an extension for connecting an air pipe, a piston disposed to reciprocate in said cylinder, and a spring arrangement tending to keep said piston in its position of rt, a contact device, operated by said piston, comprising a transverse bar disposed to be moved by said piston, a carrier for the contact brushes, and a spring connecting said bar and said carrier for malntaining azcontact pressure of said contact member independent of said piston and spring arrangement, a locking device for maintaining said contact member in circuit closing position during the major portion of the return stroke of the piston, means operated by said piston for releasing said locking device near the end of the return stroke of said spring independent of said plston tending to return said contact device into its inoperative osition.

4. n an electric switch operated by compressed gas, in combination, a cylinder having an extension for connecting an air' pi a piston disposed to reciprocate in said cylinder, and a spring arrangement tending to keep said piston in its position of rest, a contact device operated by said piston, and comprising a transverse bar disposed to be. moved by said piston, a contact brush carrier and a spring connecting said bar with 'said carrier, a locking device for maintaining said contact device in circuit closing position during the-major portion of the return stroke of the piston, consisting of movable latches resiliently supported and adapted to en age said transverse bar when in contact c osing position, means operated by said piston for releasing said loc device near the end of the return stro e of said piston, and a spring operating independently of said piston and spring arrangement tending to return said contact devlce into its inoperative position.

5. In an electric switch operated by compressed air, in combination, a cylinder having an extension for connecting an air pipe a piston disposed to reciprocate in said piston, and a cylinder, and a spring arrangement tending to keep said piston in its position of rest, -a contact device operated by said piston and comprising a transverse bar disposed to be moved by said piston, a contact brush carrier and a spring connecting said bar with said carrier, a locking device for maintaining said Contact device in circuit closing position independent of the return stroke of the piston and consisting of movable latches resiliently supported and adapted to engage said transverse bar when contact 

